In the novel The Seven Dials Mystery, Maria, Lady Coote is the wife of Sir Oswald. For the first part of the story, she and her husband live at Chimneys, which they had rented from the Earl of Caterham. In order to liven things up at the house, they had invited a number of young people to a house party, which provides the setting for the first few events which set the rest of the plot in motions.
Despite being married to one of the richest men in England and living in one of the finest historic country houses, Lady Coote is repeatedly described as a "tragic" person. She had "large, mournful eyes and a deep voice." Even Lord Caterham likened her to Mrs Siddons (a famous 18th century tragic actress).
While she looked as though she had some secret sorrow in her life, in fact this is very far from being the case. She had no trouble in her life and had followed her husband's rise from humble beginnings to extreme wealth. The wealth had however made her lonely and she longs for the old days when they lived in a tiny house and were happy together. In Chimneys she has no one to talk to and was constantly intimidated by the servants. Her completely unsuccessful efforts to manage MacDonald the gardener is contrasted with the ease with which "Bundle" later commands him to do her will on exactly the same topics.